Smith Craig, Morscher Greg
NASA Glenn Research Center, Cleveland, Ohio.
The University of Akron, Akron, Ohio.
Int J Appl Ceram Technol. 2017 Mar;14(2):228-235. doi: 10.1111/ijac.12627.
The resistance of Sylramic-iBN and Hi-Nicalon SiC fiber tows was measured at elevated temperature in air. Resistivity could not be directly measured, since the fibers passed through a furnace with varying temperature along the length. The resistivity of the isothermal section of the fiber tow was modeled by a series circuit of finite elements. Existing data for Hi-Nicalon resistivity vs temperature was used to verify the model and then extend it to Sylramic-iBN, for which there is no literature data readily available. The model matched experimental values with low overall error (<±14%). Fiber resistivity decreased by more than two orders of magnitude when heating from 25°C to 1400°C. Sylramic-iBN tow resistance was also measured during a 500 hour hold at 1315°C. The resistance increased by more than 140% during heat treatment. The resistance change correlated well with the decrease in SiC fiber diameter that resulted from oxidation.
在空气中对Sylramic-iBN和Hi-Nicalon SiC纤维束在高温下的电阻进行了测量。由于纤维沿长度方向穿过温度变化的炉体，无法直接测量电阻率。纤维束等温段的电阻率通过有限元串联电路进行建模。利用Hi-Nicalon电阻率与温度的现有数据对模型进行验证，然后将其扩展到Sylramic-iBN，目前尚无现成的文献数据。该模型与实验值匹配，总体误差较小（<±14%）。当从25°C加热到1400°C时，纤维电阻率下降了两个多数量级。还在1315°C下保温500小时期间测量了Sylramic-iBN束的电阻。热处理期间电阻增加了超过140%。电阻变化与氧化导致的SiC纤维直径减小密切相关。
